This invention relates to a suction head which, when attached to a suction source, may be used for vacuum cleaning the bottom of a swimming pool.
In sweeping the bottom of a swimming pool, it is known to utilize suction cleaning systems comprising a flexible suction line, which communicates with a suction source such as the pool circulation pump, connected to a suction head which distributes the suction over the pool bottom beneath the suction head. Accumulations of dirt on the bottom of the pool, such as particulate material, leaves and the like, which will be collectively referred to hereinafter as "silt," are drawn up the suction line out of the pool for removal. The suction head is usually moved manually across the pool bottom by a handle pivotally attached to the suction head.
Applicant's prior U.S. Pat. No. 3,273,188 discloses such a device made of a flexible plastic material allowing the suction head to conform to curved surfaces on and adjacent to the pool bottom, thereby maintaining a nearly uniform and constant separation between the suction head and the pool surface in these curved regions so that continued effective utilization of the available suction pressure can be achieved. A further advantage of the flexible suction head is that marring or chipping of the plaster surface of the pool is avoided. Another prior pool sweep of a related nature is disclosed in applicant's prior U.S. Pat. No. 3,805,309.
Although these prior devices have performed gratifyingly, a not infrequent problem with suction heads made of flexible material occurs because the plate-like nature of the suction head platform causes it to flex downwardly in the region of greatest suction, namely, the central region of the sweep where the suction line attaches to the platform. The downward flexing in the central region is also contributed to by pressure applied by the operator to the pole to move the pool sweep. This downward flexing may at times be sufficient to bring the underside of the platform into contact with the pool surface, resulting in a phenomenon known as clamping. This clamping, when it occurs, restricts the mobility of the suction head along the pool surface. Clamping can also damage the plaster surface of the pool, the suction source and the suction head. Further, clamping greatly reduces the efficiency of the cleaning operation because the suction source must normally be temporarily deactivated upon each clamping occurrence in order to free the suction head for motion.
The clamping phenomenon is most prevalent in commercial installations, which employ especially strong circulation pumps, and the resulting damage to pools and suction devices, together with the aforementioned inefficiencies mean undesired economic loss for swimming pool maintenance operators. Various approaches have been heretofore available to alleviate the clamping problem.
One approach has been to employ a suction head made of a rigid material, such as those formed primarily of metal which were the most frequently marketed variety less than a decade ago. However, while foreclosing any problems with clamping, the metal suction heads have the disadvantage of not readily conforming to curved surfaces at or near the pool bottom and, furthermore, they have a tendency to chip and mar the plaster surface of the pool. It is desirable to not sacrifice the flexibility of the plastic suction head in solving the clamping problem.
Another approach is to elevate the flexible suction head sufficiently high above the pool surface so that the suction force will be insufficient for clamping to occur. This approach necessarily results in reduced vacuuming efficiency due to the loss of suction force and it is desirable to maintain the suction head in close proximity to the pool surface in order to make most efficient use of the suction pressure.
Thus it is a concern of pool maintenance operators to be able to take advantage of the full suction pressure while utilizing a suction head which is flexible so as to conform to curved surfaces on the pool and which will not tend to damage the plaster surface of the pool.